The isolation of cells from mammalian organs has wide-ranging application in medicine, as isolated cells can be manipulated and used for producing chemicals, for degrading chemicals, or in medical devices, such as artificial organs. To achieve these goals, it is important that cells can be isolated in high yield and in relatively the same relative proportions as they exist in the organ.
For example, a liver from a pig weighing approximately 30 pounds typically weighs about 535 grams and encompasses a minimum of about 45.times.10.sup.9 hepatocyte cells. The cell recovery from standard procedures for isolating hepatocytes from porcine livers averages only about 14.times.10.sup.9 viable cells, however, with a viability of 89% per liver (IND-Bioartificial Liver and Perfusion Circuit, Vol. II, Section 7.D). The standard procedures entail pumping various buffers through the vascular network of the organ. This process is called perfusion. The buffers are necessary for maintaining the viability of the cells after the host animal has been euthanized. An enzyme breaks down connective tissue within the organ that serves to keep the organ intact and the relative position of the cells fixed within the organ during the life of the host.
Additionally, the relative proportions of cells from the different zones of the organ are often highly variable among the cells isolated by use of the standard methods when all lobes of the liver do not digest completely. Since the cells from each of the various zones often have different properties and activity, the bulk properties of the cells isolated by the standard methods can vary greatly.